@E3roa
Glad you like the idea of Houndour as Ash's fire type, I wanted to give him some types he didn't have in Johto originally since his Johto team very much always felt like Kanto version 2 because of all the starters again, so giving him a dark and fire type made for an interesting idea.
"So why is that when we finally make it to Azalea Town, you want to go back to the canyon?" Ash asked.
"The Nurse Joy said Kurt was out working and wouldn't be home today, so while we're waiting I figured I'd go for another rare Pokemon." Casey said.
"But didn't you send Qwilfish back to your family?" Molly asked.
"Look, I'm still not sure quite what I want to do for my journey, but these are fun little side things to do in the mean time." Casey pointed out.
"So what are we looking for this time?" Ash asked. "I don't see any group of Pokemon swarming about."
"No, if what I read is correct, then what we're looking for is underground." Casey explained.
"Yeah, Casey, unless you've forgotten, none of our Pokemon can go underground, at least not easily." Molly reminded.
"No, but what if we lured them to us." Casey said.
"I'm still not following you." Ash said.
"Yeah, I'm lost on this too." Molly admitted.
"Chikorita time to show off your new move, use Sweet Scent!" Casey called out.
Chikorita came out of his Pokeball, whipping their leaf back and forth, releasing a inticing smell that Pikachu perked up instantly from.
"Well it works on PIkachu." Ash commented with a laugh.
"Not who I'm going for, look over there." Casey said, seeing a mound of dirt slowly raise up. "Chikorita keep it up!"
Slowly a small drill came burrowing out of the ground before dipping back in.
"Houndour, let's help out, once it appears, use Bite!" Ash called out.
Houndour got at the ready, raring his legs back and baring his fangs.
A Pokémon's head popped out of the ground, as Houndour leapt at it, only for it to disappear back underground.
"Maybe we need something more subtle." Molly recommended.
"And what would that be?" Casey asked.
"Maybe paralysis?" Molly offered. "Mareep, come on out!"
"Alright Chikorita use Sweet Scent again, full power!" Casey called out.
Chikorita released an even greater scent, sending Houndour into a frenzy.
"Houndour no!" Ash yelled, grabbing the fire type. "Return!" Houndour immediately went back into his Pokeball, as Ash gave a sigh of relief. "Sorry about that, I guess Houndour really likes that smell."
"Guys, look." Molly said, pointing in the distance as a Pokemon stuck their head up once more. "Mareep use Thunder Wave!"
Mareep sent out a small amount of electricity only for it to get absorbed by the ground the Pokemon was still mostly submerged in.
"Okay, that still didn't work, we're running out of ideas." Casey groaned, trying to think up a plan.
"What if we made it so the ground wouldn't just dissipate the electricity." Ash offered. "Water is really weak to electricity so what if we wet this entire area and then draw the Pokemon out and paralyze it?"
"That's, actually not a bad idea, it might just work." Casey realized. "What do you think Molly?"
"It would have to be thorough, like way more thorough than you think." Molly said thinking.
"Alright then, Squirtle come on out and use Hydro Pump everywhere!" Ash called out.
Squirtle came out of his Pokeball, unleashing a massive Hydro Pump across the ground in front of them, fully soaking the dirt.
"Chikorita, let's try it again!" Casey exclaimed.
"Chik-A. Chik-A!" Chikorita chanted, letting out the enticing scent as the Pokemon once again poked it's head up from the ground.
"Mareep use Thunder Wave!" Molly called out.
Small sparks shot across the muddied ground, knocking the wild Pokemon out of it's hole.
"What is that?" Molly asked, taking out her Pokedex.
'Dunsparce, the Land Snake Pokemon, a Normal type. If spotted, it escapes by burrowing with its tail. It can float just slightly using its wings.' Molly's Pokedex explained.
"Cool." Ash said in shock.
"Now Chikorita use Vine Whip!" Casey called out.
Chikorita sent out two vines, tossing the Dunsparce into the air.
"Now use Razor Leaf!"
With Dunsparce still in the air, Chikorita sent out a series of leaves, striking the normal type while it was falling, knocking it around.
"Now use Tackle!" Casey called out.
Chikorita slammed into the Dunsparce, knocking it into a boulder causing large amounts of damage.
"Now Pokeball, go!" Casey called out.
'Ding, ding, ding.'
"Congrats on another rare catch." Ash admitted. "Though maybe next time try and do it without my help."
"Hey I had Qwilfish handled all on my own, and I could've gotten Dunsparce if you didn't keep trying to butt in." Casey remarked.
"Please, you sent Qwilfish back just in time to try and catch a Dunsparce, if I wasn't helping you would still be struggling to catch it for several more hours!" Ash pointed out.
"Typical Ash, always wanting to prove he can be the hero to save the day, well news flash, you don't have to be that every single time." Casey argued.
"WILL YOU TWO SHUT UP!" Molly shouted. "Seriously, this is getting ridiculous! Every other day I deal with you two bickering, but you know what I think?"
"What?" Ash asked.
"I think the only reason you try and butt in and be a hero is because you like trying to be that for her, but at the same time you don't want her to feel that she has to rely on you. And Casey, seriously, just admit you like him helping out and being there for you, this is getting old." Molly groaned, walking off.
"Where are you going?" Casey asked.
"The Pokemon Center, to get away from you two!" Molly scolded.
Author's notes
Yes, just like with Qwilfish and the fisherman on the north side of Union Cave, on the south end of it there is a Hiker in Gold, Silver and Crystal who will call you to let you know about Dunsparce swarms. Obviously these Pokemon are only making minor appearances as needed, but it's a fun way to give Casey some diversity for any little competitions that Johto had later on.
Casey's Current Team and their Moves
Chikorita: Razor Leaf - Vine Whip - Tackle - Sweet Scent
Dunsparce: Dig